optimized frame limit sleep

* calculate idealFrameTime only when needed
* only create a new Stopwatch when needed
* disallow wait times > 1 second

OpenRA.Game/Game.cs

@@ -420,6 +420,12 @@ namespace OpenRA
 		static bool quit;
 		public static event Action OnQuit = () => { };
 
+		static double idealFrameTime;
+		public static void SetIdealFrameTime(int fps)
+		{ 
+			idealFrameTime = 1.0 / fps;
+		}
+
 		internal static void Run()
 		{
 			if (Settings.Graphics.MaxFramerate < 1)
@@ -428,19 +434,22 @@ namespace OpenRA
 				Settings.Graphics.CapFramerate = false;
 			}
 
+			SetIdealFrameTime(Settings.Graphics.MaxFramerate);
+
 			while (!quit)
 			{
-				var idealFrameTime = 1.0 / Settings.Graphics.MaxFramerate;
-				var sw = new Stopwatch();
-
-				Tick(orderManager);
-
 				if (Settings.Graphics.CapFramerate)
 				{
-					var waitTime = idealFrameTime - sw.ElapsedTime();
+					var sw = new Stopwatch();
+
+					Tick(orderManager);
+
+					var waitTime = Math.Min(idealFrameTime - sw.ElapsedTime(), 1);
 					if (waitTime > 0)
 						System.Threading.Thread.Sleep(TimeSpan.FromSeconds(waitTime));
 				}
+				else
+					Tick(orderManager);
 			}
 
 			OnQuit();

OpenRA.Mods.RA/Widgets/Logic/SettingsLogic.cs

@@ -156,6 +156,7 @@ namespace OpenRA.Mods.RA.Widgets.Logic
 				int.TryParse(frameLimitTextfield.Text, out fps);
 				ds.MaxFramerate = fps.Clamp(20, 200);
 				frameLimitTextfield.Text = ds.MaxFramerate.ToString();
+				Game.SetIdealFrameTime(ds.MaxFramerate);
 			};
 			frameLimitTextfield.OnEnterKey = () => { frameLimitTextfield.YieldKeyboardFocus(); return true; };
 			frameLimitTextfield.IsDisabled = () => !ds.CapFramerate;
@@ -181,6 +182,7 @@ namespace OpenRA.Mods.RA.Widgets.Logic
 				gs.ShowShellmap = dgs.ShowShellmap;
 
 				ds.CapFramerate = dds.CapFramerate;
+				Game.SetIdealFrameTime(ds.MaxFramerate);
 				ds.MaxFramerate = dds.MaxFramerate;
 				ds.Language = dds.Language;
 				ds.Mode = dds.Mode;